This invention relates to variable buoyancy apparatus having improved stability against rolling. The invention may be applied to rigs for use in salvage but in its broadest aspect is simply concerned with adjusting the buoyancy and stability of any floating vessel or vessel immersed in a liquid by providing such vessel with novel floatable members of particular adjustable disposition with respect to the vessel.
U.S. Pat. No. 1,691,738 (Powell) describes an apparatus for use in recovering articles stranded in water or submerged articles or materials, which apparatus comprises particular pontoon structures the buoyancy of which can be varied and each of which have arms mounted thereon, all of the arms being connected to tong-like gripping members, the arms being connected by means of a pivot and being so arranged as to oppose the tong-like gripping members such that the buoyancy of the pontoons can can varied and the tong-like gripping members caused to come together in a tong-like action. Unfortunately, such structures, when in use without other guiding means, tend to be unstable and to exhibit excessive rolling and lack of control. Exact buoyancy control is necessary in these circumstances, and this can be a difficult matter to achieve practice. The Powell apparatus employs buoyed anchors connected to winches located on each end of each pontoon to guide the apparatus over the vessel to be recovered. These winches are controlled by an operator in a special chamber in the apparatus.
U.S. Pat. No. 2,280,547 (Scofield) discloses a device for raising sunken vessels using pivoting opposed units which include floats and which together provide a jaw-like action for salvage purposes. However, there is no suggestion of employing floatable members to compensate for rolling tendencies in the manner of this invention.
In the present invention, by contrast, by carefully positioning pivotable floatable members around an apparatus which is, in use, at least partially submerged, and enabling these members to pivot in a particular manner, a greatly enhanced degree of control is achieved and operations under water may be effected without undue rolling.